This R01 grant proposal is a revised version of a response to PA-00-016 "Research on Adherence to Interventions for Mental Disorders." The project (a) evaluates a culturally adapted, family-based intervention designed to promote treatment adherence among Mexican-Americans with schizophrenia using a randomized, controlled design in a public mental health setting, and (b) tests hypotheses about the applicability of Ajzen's theory of planned behavior (TPB), the conceptual foundation for the intervention's key constructs, to the study of treatment adherence. This conceptual model was selected for study because its emphases on the important roles of subjective norms and perceived behavior control are highly germane to the study population and to the proposed intervention. Mexican-Americans with schizophrenia and their families will be entered into the study during a psychiatric hospitalization and followed after discharge for two years. Subjects will be randomly assigned to either: 1) one year of multiple family groups that emphasize the importance of attitudes towards adherence, subjective norms, and self-perceived and actual adherence skills in maintaining adherence, added to ongoing customary outpatient care; 2) one year of standard multiple family groups added to customary outpatient care; or 3) customary outpatient care only (monthly pharmacotherapy sessions and additional services as clinically needed). Evaluations will be made at baseline and every four months for two years of actual adherence behaviors (using a multi-dimensional approach that integrates behavioral measures with multiple informants), and of the postulated mediating factors based .on the project's theoretical model: intentions to adhere to treatment; decision-making processes used to arrive at this intention; perceived subjective norms (i.e., perceptions regarding their relatives' preferences regarding treatment adherence; real and perceived ability to acquire, maintain, and utilize treatment adherence skills; attitudes towards the illness and its treatment; levels of psychopathology, and other important outcomes (e.g., social functioning, quality of life, relapse and rehospitalization rates). Key relatives will be assessed during those same time frames to determine their understanding of how and why they influence the patient's actions; their attitudes towards their mentally ill relative; their knowledge and views of schizophrenia; their roles as collaborating participants in the treatment process; and their expectations with regard to their relative's treatment and recovery. The results will advance the understanding of the factors that affect adherence to treatment for Mexican, Americans with schizophrenia, and, if the treatment were effective, would add a new tool for improving treatment adherence in this population.